This invention relates generally to centrifuges, and more particularly to a solid bowl decanter centrifuge.
Decanter centrifuges are well known, and usually include a rotating centrifuge bowl in which a screw conveyor revolves at a slightly different speed. Such centrifuges are capable of continuously receiving feed in the bowl and of separating the feed into layers of light and heavy phase materials which are discharged separately from the bowl. The screw conveyor structure, rotating at a differential speed with respect to the bowl, moves the outer layer of heavy phase material to a discharge port usually located in a tapered or conical end portion of the bowl. Centrifugal force tends to make the light phase material discharge through one or more ports usually located at the opposite end of the bowl.
Efficient centrifugal separation requires the light phase material be discharged containing little or no heavy phase material, and the heavy phase material be discharged containing only a small amount of light phase material. For example, if the light phase material is water and the heavy phase material soft solids, it is preferred that fairly dry solids and clean water be separately discharged.
Decanter centrifuges have many varied industrial applications. For example, they are used in the oil industry to process drilling mud to separate undesired drilling solids from the valuable liquid mud. In such applications, decanter centrifuges have the advantage of being less susceptible to pluggage by solids than other kinds of centrifuges. Additionally, decanter centrifuges may be shut down for long or short periods of time and then restarted with minimum difficulty, unlike most other centrifuges which require cleaning to remove dried solids.
There are many applications in the oil industry and elsewhere in which the decanting centrifuge must process the solids/liquid mixture at extraordinarily high feed rates. When the basic conventional design is modified to accommodate such feed rates, it has been found that high torques are encountered, the energy required to process the mixture becomes prohibitive, and the physical size of the centrifuge becomes prohibitive.
Additionally, as larger feed volumes are processed in a given centrifuge machine, the clarification capability of the centrifuge diminishes rapidly due to decreased relative settling area, partial-acceleration or nonacceleration (slippage) of the feed fluid (the solids/liquid mixture), deceleration of the fluid caused by fluid movement through the conveyor, and turbulence created by the movement of large volumes of fluid through the conventional helix of conventional conveyor flights.
Thus, there is a need for a decanter centrifuge capable of high capacity continuous operation at elevated feed rates and volumes.